From digitalisation to high definition

A digital television network is a communication network that consists of three functional elements. In assembly of a multiplex, television channels of programme licence-holders and other content are combined to form one multiplex. Next, the transmission, combined in a multiplex, is sent via the transmission network to regional transmission centres. Finally, television broadcasts and other information are sent aerially with radio transmitters for reception by the general public.

Digital television broadcasts were launched in Finland in the autumn of 2001, and analogue television broadcasting in the terrestrial networks ceased completely on 1 September 2007. As the distribution technology changed from analogue to digital, the volumes of transmittable programme content grew manifold. Thanks to digitalisation, one

transmission network can now transmit a full multiplex instead of a single television channel. The number of television channels grew from four to over 20. This development was made possible by the considerably higher spectrum efficiency and transmission speed of digital distribution technology, as well as the benefits created by digital audio and video compression technology.

Digital television broadcasting distribution and compression technology has continued to evolve, further increasing the volumes of transmittable content. At the same time, viewer demands for image quality have grown in line with television sets’ screen sizes.

In 2011, second-generation DVB-T2 distribution technology was introduced, brought in alongside first-generation DVB-T technology. Multiplexes A, B, C and E use DVB-T technology and MPEG2 video compression technology. Multiplexes D, F and G, and VHF A, VHF B and VHF C use DVB-T2 technology with MPEG4 video compression technology. One multiplex using DVB-T and MPEG2 technologies can transmit 6–9 standard-quality television channels. One multiplex using DVB-T2 and MPEG4 technologies can transmit 10–15 standard-quality television channels or 6–7 high-definition channels. Switching to high definition quality, a process that is now underway, has in fact led to surplus capacity being used, instead of increasing the amount of content, to improve image quality, or to their combination.

The figure below depicts the proliferation of high definition in television operations. Approximately 1,066,000 households have high-definition receivers (Full HD or HD-ready), and roughly 75,000 households subscribe to HD channels.

Figure 18: HD in television-using households (source: Finnpanel, TV Households).

11.1.1 Distribution technology

Work on the DVB-T2 standard for terrestrial television was completed in 2009. Many countries are already transmitting with DVB-T2. In Finland, transmissions began in 2011. The DVB-T2 transmission standard enables standard quality, high definition and mobile television services.

In the summer of 2011, a new version of the DVB-T2 standard was published, including the T2-Lite profile, which facilitates mobile and portable reception. The new profile also

introduces support for various services and methods of reception in the same multiplex. The same multiplex can be used for sending high-definition services for fixed reception as well as mobile television or sound-broadcasting services for mobile reception. With T2-Lite, the equipment manufactured for mobile television or sound broadcasting use can be simpler. As tablet computers become widespread, they may become a significant channel of media content distribution.

Increasing deployment of DVB-T2 technology provides television operations with opportunities for expansion thanks to faster transmission, more flexible technology, and improved spectrum efficiency. When DVB-T2 becomes commonplace, it could provide a solid platform for the transmission and reception of all public communication services. The international DVB community is developing the new DVB-NGH (Next Generation Handheld) mobile-television standard. The purpose of the new standard is to facilitate the improved distribution of rich content over mass-communication networks. The convergence of television distribution, satellite distribution, and wireless broadband is also an objective of the standard. DVB-T2 technology and the T2-Lite profile in particular already fulfil many of the objectives of this development work. At the same time, the future utilisation of all-new technologies, such as multi-antenna or hybrid technologies, is being investigated. The standard is expected to be ready in 2013 or 2014. It is possible that the NGH standard will be utilised commercially during the coming licence term. In terms of frequency use, it does not appear that the NGH standard would differ markedly from DVB-T2 technology. Also, NGH technology can be used in the same multiplex as DVB-T2 technology.

11.1.2 Compression technology

High-definition television is today transmitted with MPEG4 AVC compression technology. A new standard, HEVC (High Efficiency Video Coding), is being developed for video compression, estimated to double the efficiency of the compression technology that follows the current standard. HEVC technology is planned to become the compression technology that will enable, amongst other things, transmission in ultra-high-definition quality (i.e., for UHDTV). The new compression technology standard is expected to be ready in 2013.

Utilisation of HEVC video compression technology would mean that the television sets currently used would need to be replaced. For this reason, it is not likely that HEVC technology will replace the compression technologies now used in television broadcasting. It is fair to assume that the MPEG4 AVC standard, released in 2003, will remain the compression technology used by high-definition channels for a long time to come.